1 files changed, 25 insertions, 0 deletions
diff --git a/third_party/rust/pin-utils/src/stack_pin.rs b/third_party/rust/pin-utils/src/stack_pin.rs
new file mode 100644
index 0000000000..8a1ed2c5af
--- /dev/null
+++ b/third_party/rust/pin-utils/src/stack_pin.rs
@@ -0,0 +1,25 @@
+/// Pins a value on the stack.
+///
+/// # Example
+///
+/// ```rust
+/// # use pin_utils::pin_mut;
+/// # use core::pin::Pin;
+/// # struct Foo {}
+/// let foo = Foo { /* ... */ };
+/// pin_mut!(foo);
+/// let _: Pin<&mut Foo> = foo;
+/// ```
+#[macro_export]
+macro_rules! pin_mut {
+    ($($x:ident),* $(,)?) => { $(
+        // Move the value to ensure that it is owned
+        let mut $x = $x;
+        // Shadow the original binding so that it can't be directly accessed
+        // ever again.
+        #[allow(unused_mut)]
+        let mut $x = unsafe {
+            $crate::core_reexport::pin::Pin::new_unchecked(&mut $x)
+        };
+    )* }
+}